Bug 1062066 (Part 2) - Add a Downscaler API to clear a row. r=tn

iaxat · Sep 9, 2015 · c3bb377 · c3bb377
1 parent ae4622a
commit c3bb377
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diff --git a/image/Downscaler.cpp b/image/Downscaler.cpp
@@ -148,6 +148,16 @@ GetFilterOffsetAndLength(UniquePtr<skia::ConvolutionFilter1D>& aFilter,
                           aFilterLengthOut);
 }
 
+void
+Downscaler::ClearRow(uint32_t aStartingAtCol)
+{
+  MOZ_ASSERT(int64_t(mOriginalSize.width) > int64_t(aStartingAtCol));
+  uint32_t bytesToClear = (mOriginalSize.width - aStartingAtCol)
+                        * sizeof(uint32_t);
+  memset(mRowBuffer.get() + (aStartingAtCol * sizeof(uint32_t)),
+         0, bytesToClear);
+}
+
 void
 Downscaler::CommitRow()
 {

diff --git a/image/Downscaler.h b/image/Downscaler.h
@@ -82,6 +82,9 @@ class Downscaler
   /// Retrieves the buffer into which the Decoder should write each row.
   uint8_t* RowBuffer() { return mRowBuffer.get(); }
 
+  /// Clears the current row buffer (optionally starting at @aStartingAtCol).
+  void ClearRow(uint32_t aStartingAtCol = 0);
+
   /// Signals that the decoder has finished writing a row into the row buffer.
   void CommitRow();
 
@@ -150,6 +153,7 @@ class Downscaler
   }
 
   uint8_t* RowBuffer() { return nullptr; }
+  void ClearRow(uint32_t = 0);
   void CommitRow() { }
   bool HasInvalidation() const { return false; }
   DownscalerInvalidRect TakeInvalidRect() { return DownscalerInvalidRect(); }